From owner-freebsd-small@FreeBSD.ORG Sun Jun 18 19:09:29 2006 Return-Path: X-Original-To: freebsd-small@freebsd.org Delivered-To: freebsd-small@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 7477E16A47B for ; Sun, 18 Jun 2006 19:09:29 +0000 (UTC) (envelope-from brucem@mail.cruzio.com) Received: from cruzio.com (dsl-63-249-85-132.cruzio.com [63.249.85.132]) by mx1.FreeBSD.org (Postfix) with ESMTP id 0996A43D46 for ; Sun, 18 Jun 2006 19:09:28 +0000 (GMT) (envelope-from brucem@mail.cruzio.com) Received: from mail.cruzio.com (localhost [127.0.0.1]) by cruzio.com (8.12.10/8.12.10) with ESMTP id k5IJCgxm000484 for ; Sun, 18 Jun 2006 12:12:42 -0700 (PDT) (envelope-from brucem@mail.cruzio.com) Received: (from brucem@localhost) by mail.cruzio.com (8.12.10/8.12.10/Submit) id k5IJCfii000483 for freebsd-small@freebsd.org; Sun, 18 Jun 2006 12:12:41 -0700 (PDT) (envelope-from brucem) Date: Sun, 18 Jun 2006 12:12:41 -0700 (PDT) From: "Bruce R. Montague" Message-Id: <200606181912.k5IJCfii000483@mail.cruzio.com> To: freebsd-small@freebsd.org Subject: Re: Web site updated... X-BeenThere: freebsd-small@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Dedicated and Embedded Systems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 18 Jun 2006 19:09:29 -0000 Hi, re: > ... AMD bought the > Geode technology from Via technology a couple of years ago, ... My impression (might be wrong on some details) was that Cyrix developed the basic low-power+ hypervisor-assisted-x86 (the Geode). The Geode hypervisor (VSA; Virtual System Architecture, or somesuch) was used not to provide a means to run multuple virtual machines but to implement virtual devices that would normally require additional hardware (that is, the code in controllers on peripheral boards was "moved" into hypervisor drivers, enabling the hypervisor-enabled CPU to emulate the device programming interface and also directly drive various "transducers" normally controlled by external controllers. This was intended to provide minimal-sized "system-on-a-chip" systems. The video framebuffer and CPU cache were integrated and under control of the hypervisor (the CPU contained an integrated video controller). This worked, but the large x86 pin-out and required capacitors bounded how small the system could actually be made. Cyrix was sued by Creative Labs for, in effect, reverse engineering the Sound Blaster. Cyrix lost, which seems to have largely been the end of the effort to make a dirt-cheap "PC motherboard on a chip"; the chip was repositioned as an embedded device and settop-box controller. National purchased Cyrix and tried to push designs based around tight-coupling the Geode to National's peripheral chips (such as ethernet controllers). The non-Geode part of Cyrix ("stock" x86 CPUs) was sold to the Taiwanese company Via. Via seems to have mostly wanted the brand name and pieces of IP; Via's CPU technology does not seem derived directly from Cyrix. National sold the Geode to AMD a few years ago. The Geode/VSA is an interesting use of a hypervisor to make a system as small as possible. The original VSA was limited to 64K in size. There is now a VSA II, don't know if it has the same limitation. A big problem with the use of such a hypervisor to shrink systems as small as possible is the 2-layers of drivers that result (first the driver that talks to the emulated device, then the real driver in the hypervisor). Also the hypervisor driver's may not provide the "real-time" or direct device access functionality that embedded applications may require. I think many of the would-be users of the embedded Geode would have liked to only use a minimal number of virtualized devices, while having the ability/doc to write their own driver's for the raw hardware driven by the CPU... - bruce